Carburetor de-icer



April 7, 1964 R- L. HAMMERSCHMIDT CARBURETOR DE-ICER Filed 'Sept. 18, 1961 INV EN TOR. Rudolph L. Hammerschmidf A TTORNE Y United States Patent ()fi ice 3,128,321 Patented Apr. 7, 1964 3,128,321 CARBURETOR DE-iER Rudolph L. Hammerschmitit, Contra Costa County, Calif. (R6. Box 727, Wa nut, tlaiif.) Fiietl Sept. 18, 1961, Ser- No. 138,979 4 Claims. (Ci. 261--142) The present invention relates to carburetors for internal combustion engines and more particularly to means for preventing the formation of ice in carburetors.

In the operation of internal combustion engines during cold humid weather, difficulties may arise from the formation of ice within the carburetor venturi and on fuel jets and throttling mechanisms. This condition may occur when the air passing through the carburetor is below the dew point and below freezing temperature. The forming of ice is aggravated by the pressure drop undergone by air entering the venturi and by the considerable absorption of heat by the evaporating fuel within the carburetor.

A carburetor is usually heated during a period of engine operation to the point where icing is not a problem. Thus the difficulties attendant carburetor icing are most frequently encountered in starting up a cold engine. Depending on the particular portion of the carburetor which is affected, icing may act to block the feeding of fuel into the venturi throat, reduce the throat cross section, or interfere with the action of the throttle mechanism. These effects may reduce engine power output, fuel economy and response and in severe cases will prevent operation altogether.

Except under extreme weather conditions icing effects are not critical in the operation of conventional or stock carburetors. In most such units, fuel enters at a point well above the throttle plate and exerts a washing action. However, special forms of carburetor have recently been introduced which give superior performance but which are also particularly prone to icing. The apparatus described in US. Patent 2,236,595, entitled Carburetor and issued to John Robert Fish April 1, 1941, is representative of these icing prone carburetors.

The Fish carburetor, in comparison with more conventional types, gives a much greater control over mixture ratios throughout a broad range of engine speeds and therefore considerably increases fuel economy and engine performance. In addition to these advantages, the Fish carburetor is much less complex than standard carburetors and less subject to mis-adjustment and mal-function.

Considerable difficulty has been experienced in the operation of the Fish carburetor in cold humid climates from icing, particularly in the region of the throttle plate. This arises in part from the fact that fuel enters the venturi through the shaft on which the throttle plate turns and is emitted from a series of apertures in the shaft which are adjacent the plate. Because of this structure, the cooling effect of the evaporating fuel tends to be concentrated in the region of the throttle mechanism and rapid formation of ice occurs where the atmospheric conditions are favorable.

Previous attempts to forestall icing in carburetors have taken the form of providing means for heating the air entering the carburetor or for heating the fuel in the float chamber. Neither of these techniques is completely satisfactory in an internal combustion engine carburetor. Heating of the air is cumbersome and inefficient and heating of the fuel has only a very minor beneficial effect while tending to promote undesired expansion and evaporation of fuel.

The present invention provides a much more efficient, compact and simple means for forestalling icing in carburetors and is of particular value for making the Fish carburetor reliable under all weather conditions.

The invention provides for the direct application of heat to the carburetor venturi housing by the disposition of a heating element thereat. Preferably a circular shaped electrical heating element is utilized which element is mounted in coaxial position on the venturi. The element may conveniently be mounted in a groove formed around the interior surface of the venturi throat or may be mounted around the outside of the venturi housing, the effect in either case being to directly heat the region of the carburetor structure at which ice formation tends to occur.

To provide for energization of the heating element, one end thereof may be grounded to the carburetor body and the other end is connected to a source of electrical power, for example, a battery. To avoid inadvertent operation of the de-icer while the engine is not operating, the connection of the heating element to the battery is preferably made through a suitable switch, such as an ignition switch, and an additional switch may be provided in order that the de-icer may be inactivated during engine opera tion when weather conditions do not require its use.

The foregoing structure is a very compact, economically manufactured unit which effectively eliminates carburetor icing problems under any Weather conditions. The device may readily be installed on existing carburetors as well as being built into new units. In particular, the invention removes the difficulty heretofore encountered with Fish type carburetors and allows the superior performance thereof to be realized without regard to atmospheric conditions.

It is accordingly an object of the present invention to provide a more effective means for the prevention of carburetor icing in internal combustion engines.

It is an object of this invention to provide a means for making the Fish carburetor reliable under any weather conditions.

It is another object of the invention to provide for the direct application of heat to those portions of a carburetor which are most prone to icing.

It is still another object of the invention to provide a carburetor de-icer which is compact, efficient, economically manufactured and readily installed.-

It is a further object of the invention to provide a car buretor de-icer which may be selectively operated or deactivated when conditions do not call for the use of the same.

It is still another object of this invention to provide a de-icing unit which is readily mountable on existing carburetors and which does not interfere with the operation thereof.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood by reference to the following description taken in conjunction with the accompanying drawings of which:

FIGURE 1 is a section view of a Fish carburetor taken along the axis of the venturi thereof and showing a first embodiment of the invention mounted therein,

FIGURE 2 is a top view of the carburetor of FIGURE 1 with portions of the structure broken out to illustrate detail of the invention and with associated electrical connections shown schematically, and

FIGURE 3 is an elevation view of the carburetor showing a second embodiment of the invention mounted thereon.

Referring now to the drawing and more particularly to FIGURES l and 2 thereof, there is shown for purposes of example a carburetor 11 mounted on the intake manifold 12 of an automotive engine in the conventional manner, it being understood that the invention is equally applicable to aircraft, marine, stationary and other engines. The carburetor 11 is of the Fish type and thus includes an upright cylindrical venturi throat 13 mounted over an opening 14 in manifold 12 by suitable bolts 16 and having an upper air intake end 17 of increased diameter. A rotatable throttle plate shaft 18 extends across the throat 13 along a diameter thereof, the ends of the shaft projecting into bushings 19 which are transpierced through the wall of the throat. A radial crank arm 21 is secured to one end of the throttle shaft 18 and the standard accelerator pedal linkage connects therewith to provide for the control of the angular position of the shaft. A circular throttle plate 22, having a diameter conforming to that of the bore of throat 13, is mounted on the shaft 18 by suitable clamps 23.

The fuel feeding system of this form of carburetor includes a float chamber housing 24 secured against the side of the throat 13 opposite from crank arm 21 and having a fitting 26 at the top communicating with the engine fuel pump' outlet. A hollow float 27 is disposed within the housing 24 and when moved upward by an adequate amount of fuel in the chamber the float closes a valve 28 at the fuel inlet.

A second chamber 29 is formed at the side of the carburetor between the throat 13 and fuel chamber housing 24 and is separated from the latter by a plate 31. A leaft-ype check valve 32 is mounted at an aperture 33 in plate 31 so that fuel may flow from the float chamber 24 into the chamber 29 but may not fiow in the reverse direction. A radially directed arm 34 is mounted on the end of throttle shaft 18 within changer 29, the arm having a height and width corresponding to that of the chamber 29 so that fuel within the chamber cannot flow from one side of the arm to the other.

An arcuate groove 36 is formed in the wall of chamber 29 which is adjacent throat 13, the groove being a segment of a circle having the axis of throttle shaft 13 as a center and having a radius slightly less than the length of arm 34-. An angled internal fuel passage 37 is provided within the arm 34 one end of which passage opens into the groove 36 and the other end of which communicates with a longitudinal passage 38 in throttle shaft 18. A series of transverse passages 39 in the throttle shaft 18 provide for the ejection of fuel into the carburetor venturi throat 13.

The subatmospheric pressure within the venturi throat 13, resulting from the constriction of the air fiow therethrough, acts to draw fuel into the air stream from chamber 29 via groove 36 and passages 37, 38 and 39. in order that progressively greater amounts of fuel will be delivered as the throttle plate 22 is rotated to more open positions, the groove 36 is tapered, the groove being progressively increased in both width and depth in the direction in which arm 34 travels as the throttle is opened. It should be noted that the mechanism has an automatic action equivalent to that of the acceleration jets on a standard carburetor since movement of the arm 34 towards the open throttle position acts to force a charge of fuel from chamber 29 into the passage 37 and thus into the venturi air stream.

A more complete description of the Fish carburetor and the operation thereof may be found in the hereinbefore mentioned US. Patent No. 2,236,595, the foregoing brief description of basic features of the unit being sufiicient for an understanding of the application of the invention thereto. As previously noted, this specialized form of carburetor gives superior performance but is particularly prone to icing to the degree that the carburetor has frequently been found to be inoperable during cold humid weather conditions. It has been the practice of many users of this form of carburetor to replace the unit with a stock carburetor during the winter months.

. Considering now the application of the present invention to the carburetor, it will be found that most such units have a relative thick transition section 41 near the upper end of the throat 13 at the region where the diameter thereof changes, the section forming an upwardly facing annular bench. To receive the heating element assembly 42 of the present invention, an annular upwardly opening groove 43 may be readily formed in the section 41 on existing carburetors as well as new units.

On carburetors having a transition section 41 which is too thin-walled to permit the groove 43 to be formed therein, the wall may be thickened, to provide an equivalent groove, through the addition of metal thereon by any of the various techniques well known to those skilled in the art.

The heating assembly 42 is formed into a circular loop and is disposed coaxially within the groove 43. A suitable construction for the assembly 42 employs a single turn of resistance heating element wire 44 strung on ceramic beads 46 which serve to support the wire and to provide electrical insulation therefor. Although the beads 46 are relatively poor thermal conductors this is a desirable characteristic in the present application since it prevents too rapid or too localized heating of the carburetor body.

In a typical carburetor wherein the groove 43, and thus the Wire 44, may have a mean diameter of two and three-sixteenth inches, and where a six volt automative electrical system is employed, the wire 44 may be Nichrome of 0.018 diameter. The groove 43 may be of the order of one-eighth inch in width and three-sixteenths inch deep.

To retain the wire 44 and beads 46 in position, the groove 43 is filled with a hardenable, heat resistant plastic compound 4'7 with the surface thereof being smoothed to restore the original contour of the carburetor throat 13.

Considering now the electrical connections to the assembly 42, an insulative bushing 48 is transpierced through the wall of the throat 13, at the level of the wire 44, and a terminal post 49 extends therethrough and connects with one end of the wire. The adjacent opposite end of wire 44 is secured to a grounding pin 51 which is mounted in the inner wall surface of the throat 13. To provide energizing current to the heating element assembly 42, terminal post 49 is connected to the automobile battery 52 through the ignition switch 53. Preferably an additional manually operable switch 54 is provided between the ignition switch 53 and terminal post 49, the switch 54 being most conveniently located on the automobile dashboard 56. The additional switch 54 allows the automobile to be operated without energization of the de-icer during warm weather or under other conditions where it is not required.

In operation, the de-icer is turned on by closing switch 54 following closing of the ignition switch 53. During severe Weather conditions it may be desirable to delay starting of the engine for a brief period following energization of the de-icer in order to allow the carburetor to be pro-heated. Upon the closing of the switches 53 and 54, current from battery 52 passes through the wire,

element 44 generating heat which is conducted to the carburetor throat 13, throttle shaft 18 and throttle plate 22.

The heat is applied to those portions of the carburetor which are most prone to icing and is produced at a sufficient rate to prevent the formation of ice under the most extreme weather conditions. The de-icer structure provides this result without impeding air flow through the throat 13 or producing any deleterious effect on the operation of any of the carburetor components.

Referring now to FIGURE 3, a second structure for mounting an annular heating element assembly on a carburetor is shown, this embodiment also being highly effective in preventing the formation of ice therein. The carburetor 11 of FIGURE 3 is also of the Fish type and is similar in all its components to that hereinbefore described with reference to FIGURES 1 and 2.

The heating element assembly 57 in this embodiment is mounted externally on the carburetor throat 13 preferably at a level just below that of the throttle shaft 18'. The heating element 58 may be any of the well known commercially available rod types having a tubular outer shell 59 through which a resistance coil 61 passes and containing a packing 62 of insulative material. The element 58 is curved to encircle the throat 13' except for the portion thereof occupied by the housing of chamber 29, the element having an inner diameter similar to the outside diameter of the throat.

Heating element 58 is enclosed within an annular protective shield 63 which also encircles the above described portion of the carburetor throat 13'. Shield 63 has a cross-sectional area substantially greater than that of element 58 and is filled with a packing of thermal insulation 64 which spaces the heating element from the Walls of the shield. A downwardly extending lip 66 is formed around the lower inner rim of shield 63 through which screws 67 are transpierced to fasten the assembly 57 to the carburetor. A terminal post 68 is provided at one end of the shield 63 and connects with the heating element 58, the electrical connections to the unit being similar to those hereinbefore described with reference to the embodiment of FIGURES 1 and 2.

Upon energization of the heating element 58, the unit operates to prevent the formation of ice within the carburetor in the manner hereinbefore described. The embodiment of FIGURE 3 will be found particularly useful where the carburetor design is not readily adaptable to the internally mounted unit.

While the invention has been disclosed with respect to two exemplary embodiments, it will be apparent to those skilled in the art that numerous variations and modifications may be made Within the spirit and scope of the invention and thus it is not intended to limit the invention except as defined in the following claims.

What is claimed is:

1. Apparatus for preventing the formation of ice within the venturi throat of a carburetor of the class in which fuel is injected into the throat through passages in a throttle shaft extending thereacross comprising, in combination, a resistance heating element extending around at least a portion of said venturi throat in proximity to said throttle shaft, a quantity of electrically insulative material disposed between said element and said venturi throat for conducting heat therebetween, and means for connecting said heating element with a source of electrical current.

2. A de-icer for a carburetor of the class in which fuel is injected into the venturi passage thereof through apertures in a throttle shaft extending across said venturi passage, said de-icer comprising, in combination, a long resistance heating element formed in a curvilinear configuration and encircling at least a major portion of said venturi passage, said heating element being secured to said carburetor at a position thereon proximal to said throttle shaft, electrically insulative means isolating said heating element from said carburetor and providing for the conduction of heat therebetween, and means for passing an electrical current through said element.

3. A de-icer for a carburetor having a cylindrical venturi throat with a throttle shaft extending thereacross and having fuel jets in said throttle shaft and wherein a coaxial groove is provided around the wall of said throat in proximity to said throttle shaft, said de-icer comprising a length of resistance heating element wire disposed in said groove and encircling at least a major portion of said throat, a plurality of beads strung on said wire within said groove and spacing said wire from said wall of said throat, said beads being formed of electrically insulative material, and means for passing an electrical current through said wire.

4. In a carburetor of the class having a cylindrical venturi throat and a throttle shaft extending thereacross with fuel emitting passages in said throttle shaft, a de-icer comprising, in combination, a resistance heating element of the class having a tubular outer shell with a filler of electrically insulative material and a resistance heating wire disposed along the axis thereof, said heating element being formed in a curvilinear configuration and being disposed around the external surface of said throat encircling at least a major portion of the circumference thereof in the region of said throttle shaft, clamping means for securing said heating element in said position on said venturi throat, and means for connecting said heating element with a source of electrical current.

References Cited in the file of this patent UNITED STATES PATENTS 1,171,145 Sachs Feb. 8, 1916 2,576,401 Kimmell Nov. 27 1951 2,582,389 McDonnell Jan. 15, 1952 2,877,753 Larsen Mar. 17, 1959 FOREIGN PATENTS 571,990 France Feb. 13, 1924 209,762 Great Britain 1925 194,000 Switzerland Apr. 16, 1938 

1. APPARATUS FOR PREVENTING THE FORMATION OF ICE WITHIN THE VENTURI THROAT OF A CARBURETOR OF THE CLASS IN WHICH FUEL IS INJECTED INTO THE THROAT THROUGH PASSAGES IN A THROTTLE SHAFT EXTENDING THEREACROSS COMPRISING, IN COM BINATION, A RESISTANCE HEATING ELEMENT EXTENDING AROUND AT LEAST A PORTION OF SAID VENTURI THROAT IN PROXIMITY TO SAID THROTTLE SHAFT, A QUANTITY OF ELECTRICALLY INSULATIVE MATERIAL DISPOSED BETWEEN SAID ELEMENT AND SAID VENTURI THROAT FOR CONDUCTING HEAT THEREBETWEEN, AND MEANS FOR CONNECTING SAID HEATING ELEMENT WITH A SOURCE OF ELECTRICAL CURRENT. 